Figures for MIJ-NSR Volume 5, Article 11

Figures

Figure 1

Schematic diagram of (a) RIE, (b) ECR and (c) ICP etch platforms.

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Figure 2

Schematic diagram of high density plasma etching process.

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Figure 3

RIBE nitride removal rates as a function of Cl₂ percentage in Cl₂/Ar beams

Figure 4

GaN etch rates in RIE, ECR, ICP and RIBE Cl₂-based plasmas as a function of dc bias.

Figure 5

GaN etch rates as a function of pressure in an ICP-generated BCl₃/Cl₂/Ar plasma at 32 sccm Cl₂, 8 sccm BCl₅, 5 sccm Ar, 500 W IPC source power, dc-bias -150 V and 10°C electrode temperature.

Figure 6

GaN etch rates as a function of dc bias in an ICP-generated BCl₃/Cl₂/Ar plasma at 32 sccm Cl₂, 8 sccm BCl₃, 5 sccm Ar, 500 W ICP source power, 2 mTorr pressure and 10°C electrode temperature.

Figure 7

SEM micrographs for GaN etched at (a) -50, (b) -150 and (c) -300 V dc bias. ICP etch conditions were 32 sccm Cl₂, 8 sccm BCl₃, 5 sccm Ar, 500 W ICP source power, 2 mTorr pressure and 10°C electrode temperature.

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Figure 8

GaN etch rates as a function of ICP source power in an ICP-generated BCl₃/Cl₂/Ar plasma at 32 sccm Cl₂, 8 sccm BCl₃, 5 sccm Ar, -250 V dc bias, 2 mTorr pressure and 10°C electrode temperature.

Figure 9

GaN, InN and AlN (a) etch rates and (b) GaN:AlN and GaN:InN etch selectivities as a function of dc bias in a Cl₂/Ar ICP plasma. Plasma conditions were: 25 sccm Cl₂, 5 sccm Ar, 2 mTorr chamber pressure, 500 W ICP-source power and 25°C cathode temperature.

Figure 10

GaN and InN etch rates as a function of temperature for an ICP-generated Cl₂/H₂/Ar plasmas. ICP etch conditions were 22.5 sccm Cl₂, 2.5 sccm H₂, 5 sccm Ar, 500 W ICP source power, -250 V dc bias and 2 mTorr pressure.

Figure 11

GaN etch rates in an ICP and ECR Cl₂H₂/Ar plasma as a function of %H₂.

Figure 12

GaN etch rates in an ICP and ECR BCl₃/H₂/Ar plasma as a function of

Figure 13

GaN etch rates as a function of %N₂ for ICP-generated Cl₂- and BCl₃-based plasmas.

Figure 14

Optical emission spectra (OES) for an ICP-generated BCl₃/N₂ plasma as a function of BCl₃ percentage.

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Figure 15

GaN etch rates in an ICP BCl₃/Cl₂ plasmas as a function of Cl₂.

Figure 16

GaN, InN and AlN (a) etch rates and (b) GaN:AlN and GaN:InN etch selectivities

Figure 17

Nitride etch rates (top) and etch selectivities for InN/AlN and InN/GaN (bottom in BI₃/Ar or BBr₃/Ar discharges (750 W source power, 5 mTorr) as a function of the boron halide content.

Figure 18

Nitride etch rates (top) and etch selectivities for InN/AlN and InN/GaN (bottom) in BI₃/Ar or BBr3/Ar discharges as a function of source power.

Figure 19

Nitride etch rates (top) and etch selectivities for InN/AlN and InN/GaN (bottom) in BI₃/Ar or BBr₃/Ar discharges as a function of rf chuck power.

Figure 20

Nitride etch rates (top) and etch selectivities for InN/AlN and InN/GaN (bottom) in ICl/Ar or IBr/Ar discharges (750 W source power, 250 W rf chuck power, 5 mTorr) as a function of interhalogen content.

Figure 21

SEM micrographs of (a) GaN, (b) AlN and (c) InN etched in Cl₂-based ICP plasmas.

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Figure 22

AES surface scans of GaN (a) before exposure to the plasma, (b) at 65 W (-120 V bias) and (c) 275 W rf-cathode power (-325 V bias), 1 mTorr, 170°C, and 850 W microwave power in an ECR-generated Cl₂/H₂ discharge.

Figure 23

Schematic of GaN Schottky diode structure.

Figure 24

I-V characteristics from GaN diodes before and after H₂ (top) or N₂ (bottom) plasma exposure (150 W rf chuck power, 5 mTorr) at different ICP source powers.

Figure 25

Variation of V_B in GaN diodes (top) and dc chuck self-bias (bottom) as a function of ICP source power in H₂ or N₂ plasmas (150 W rf chuck power, 5 mTorr).

Figure 26

I-V characteristics from N₂ plasma exposed GaN diodes before and after wet etch removal of different amounts of GaN prior to deposition of the Schottky contact (top) and variation of V_B as a function of the amount of material removed (bottom).

Figure 27

I-V characteristics from GaN diodes before and after N₂ plasma exposure (500 W source power, 150 W rf chuck power, 5 mTorr) and subsequent annealing either prior (top) or subsequent (center) to the deposition of the Schottky metallization. The variation of V_B in the samples annealed prior to metal deposition is shown at the bottom of the figure.

Figure 28

I-V characteristics from samples exposed to either H₂ (top) or Ar (bottom) ICP discharges (150 W rf chuck power) as a function of ICP source power prior to deposition of the Ti/Pt/Au contact.

Figure 29

Variation of diode breakdown voltage in samples exposed to H₂ or Ar ICP discharges (150 W rf chuck power) at different ICP source powers prior to deposition of the Ti/Pt/Au contact. The dc chuck self-bias during plasma exposure is also shown.

Figure 30

Forward turn-on characteristics of diodes exposed to ICP Ar discharges (150 W rf chuck power) at different ICP source powers prior to deposition of the Ti/Pt/Au contact.

Figure 31

Wet etching rate of p-GaN in boiling NaOH solutions as a function of solution molarity.

Figure 32

Wet etching rate of Ar plasma exposed (750 W source power, 150 W rf chuck power) GaN as a function of depth into the sample.

Figure 33

I-V characteristics from samples exposed to ICP Ar discharges (750 W source power, 150 W rf chuck power) and subsequently wet etched to different depths prior to deposition of the Ti/Pt/Au contact (top) and breakdown voltage as a function of depth removed (bottom).

Figure 34

I-V characteristics from samples exposed to ICP Ar discharges (750 W source power, 150 W rf chuck power) and subsequently annealed at different temperatures prior to deposition of the Ti/Pt/Au contact (top) and breakdown voltage as a function of annealing temperature (bottom).

Figure 35

I-V characteristics from n-GaN samples exposed to ICP Cl₂/Ar (top) or Ar (bottom) discharges (500 W source power) as a function of rf chuck power prior to deposition of the rectifying contact.

Figure 36

Variations of V_B and V_F (top) and of n-GaN etching rate (bottom) as a function of rf chuck power for n-GaN diodes exposed to ICP Cl₂/Ar discharges (500 W source power).

Figure 37

I-V characteristics from n-GaN samples exposed to ICP Cl₂/Ar (top) or Ar (bottom) discharges (150 W rf chuck power, 500 W source power) as a function of plasma exposure time prior to deposition of the rectifying contact.

Figure 38

Variation of V_B in n-GaN diodes exposed to ICP Cl₂/Ar or Ar discharges (500 W source power, 100 W rf chuck power) with annealing temperature prior to deposition of the rectifying contact.

Figure 39

I-V characteristics from p-GaN samples exposed to ICP Cl₂/Ar (top) or Ar (bottom) discharges (500 W source power, 150 W rf chuck power) and wet etched in boiling NaOH to different depths prior to deposition of the rectifying contact.

Figure 40

Variation of V_B and V_F (top) with depth of p-GaN removed by wet etching prior to deposition of the rectifying contact, and wet etch depth versus etch time in boiling NaOH solutions for plasma damaged p-GaN (bottom).

Figure 41

Reverse leakage current measured at -30 V for GaN p-i-n junctions etched in ICP 32Cl₂/8BCl₃/5Ar discharges (500 W source power, 2 mTorr), as a function of dc chuck self-bias.

Figure 42

Reverse leakage current measured at -30 V for GaN p-i-n junctions etched in ICP 32Cl₂/8BCl₃/5Ar discharges (-100 V dc chuck self-bias, 2 mTorr), as a function of source power.

Figure 43

Reverse leakage current measured at -30 V for GaN p-i-n junctions etched in ICP 32Cl₂/8BCl₃/5Ar discharges (-300 V dc chuck self-bias, 500 W ICP source power, 2 mTorr), as a function of anneal temperature.